Nanocomposites, methods of making same, and applications of same for multicolor surface enhanced raman spectroscopy (sers) detections

ABSTRACT

A nanoagent for surface enhanced Raman spectroscopy (SERS) detection of a target of interest, includes one or more nanocomposites. The target of interest may include at least one tumor cell or at least one pathogen. Each nanocomposite includes at least one gold nanorod, a silver layer coated on a surface of the gold nanorod and having silver nanoparticles, a Raman reporter molecule layer assembled on the silver layer and having Raman reporter molecules, a pegylated layer coated on the Raman reporter molecule layer, and an antibody layer conjugated to the pegylated layer. The different nanocomposites of the nanoagent can be represented by different colors when SERS images are collected upon the nanoagent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of, pursuant to 35U.S.C. §119(e), U.S. provisional patent application Ser. No. 61/891,006,filed Oct. 15, 2013, entitled “MULTICOLOR SERS DETECTION AND IMAGING OFCANCER CELLS IN BLOOD USING SILVER DECORATED GOLD NANOROD,” by AlexandruS. Biris, Zeid Nima and Yang Xu, the disclosure of which is incorporatedherein in its entirety by reference.

Some references, which may include patents, patent applications, andvarious publications, are cited and discussed in the description of thisinvention. The citation and/or discussion of such references is providedmerely to clarify the description of the present invention and is not anadmission that any such reference is “prior art” to the inventiondescribed herein. All references cited and discussed in thisspecification are incorporated herein by reference in their entiretiesand to the same extent as if each reference was individuallyincorporated by reference. In terms of notation, hereinafter, “[n]”represents the nth reference cited in the reference list. For example,[3] represents the third reference cited in the reference list, namely,Nima, Z. A. et al. Single-walled carbon nanotubes as specific targetingand Raman spectroscopic agents for detection and discrimination ofsingle human breast cancer cells. Journal of Biomedical Optics 18,055003-055003 (2013).

STATEMENT AS TO RIGHTS UNDER FEDERALLY-SPONSORED RESEARCH

This invention was made with government support under grant numberW81XWH-10-2-0130 awarded by the Department of Defense. The governmenthas certain rights in the invention.

FIELD OF THE INVENTION

The invention relates generally to detections of cancer cells orpathogens, and more particularly to nanocomposites, methods of makingthe same, and applications of the same for multicolor surface enhancedRaman spectroscopy (SERS) detections and imaging of cancer cells orpathogens.

BACKGROUND OF THE INVENTION

The background description provided herein is for the purpose ofgenerally presenting the context of the present invention. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentinvention.

Targeting, imaging and treatment of cancer cells using biocompatiblenanomaerials is one ultimate goal for a versatile number of studies indifferent fields of science, engineering, and medicine [1-9].Nanomaterials are widely investigated and tested by researchers fromdifferent fields due to their unique features not observed at themacroscale of the same material [1, 2]. However, there are stillchallenges in the field to discover nanoagents that provide sensitiveand accurate detection of cancer cells.

Therefore, a heretofore unaddressed need exists in the art to addressthe aforementioned deficiencies and inadequacies.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed to a nanoagent for surfaceenhanced Raman spectroscopy (SERS) detection of a target of interest. Incertain embodiments, the nanoagent includes at least one nanocomposite.

In one embodiment, the nanocomposite includes at least one gold nanorod,a silver layer coated on an outer surface of the gold nanorod and havingsilver nanoparticles, a Raman reporter molecule layer coated on thesilver layer, a pegylated layer coated on the Raman reporter moleculelayer and having at least one of thiolated polyethylene glycol (HS-PEG),thiolated polyethylene glycol acid (HS-PEG-COOH) and HS-PEG-NHx, and anantibody layer conjugated to the pegylated layer and having molecules ofan antibody.

In one embodiment, the gold nanorod has an aspect ratio (AR) in therange of about 1-9. In one embodiment, the gold nanorod has the AR in arange of about 2-5. In one embodiment, the gold nanorod has the AR in arange of about 2.77-3.23.

In one embodiment, the gold nanorod has a length in the range of about10-100 nm and has a diameter in the range of about 1-40 nm,respectively. In one embodiment, the gold nanorod has the length in therange of about 35.20-36.80 nm and has the diameter in the range of about11.59-12.41 nm, respectively.

In one embodiment, the silver layer has a thickness in a range of about0.5-5 nm. In one embodiment, the silver layer has the thickness of about1-2 nm. In one embodiment, the silver layer has the thickness of about1.7 nm.

In one embodiment, the Raman reporter molecule layer includes4-mercaptobenzoic acid (4MBA), p-aminothiophenol (PATP),p-nitrothiophenol (PNTP), 4-(methylsulfanyl) thiophenol (4MSTP), orother molecules with unique Raman spectra and intense Raman peakintensities.

In one embodiment, the HS-PEG has a molecular weight in a range of about1.5-15 kilo Dalton (kD) and the HS-PEG-COOH has a molecular weight in arange of about 1-10 kD. In one embodiment, the HS-PEG has the molecularweight of about 5 kD and the HS-PEG-COOH has the molecular weight ofabout 3 kD.

In one embodiment, the molecules of the antibody are conjugated to thecorresponding pegylated layer through the carboxylic group of theHS-PEG-COOH or the amine group of HS-PEG-NHx.

In one embodiment, the antibody anti-epithelial cell adhesion moleculeantibody (anti-EpCAM), anti-CD44 antibody, anti-insulin-like growthfactor 1 receptor antibody (anti-IGF-1), anti-Keratin 18 antibody, orone or more antibodies specific to the target of interest.

In one embodiment, the at least one nanocomposite includes a firstnanocomposite, a second nanocomposite, a third nanocomposite, and afourth nanocomposite. The Raman reporter molecule layer of the firstnanocomposite includes 4-mercaptobenzoic acid (4MBA), and the antibodyof the first nanocomposite is anti-epithelial cell adhesion moleculeantibody (anti-EpCAM). The Raman reporter molecule layer of the secondnanocomposite includes p-aminothiophenol (PATP), and the antibody of thesecond nanocomposite is anti-CD44 antibody. The Raman reporter moleculelayer of the third nanocomposite is p-nitrothiophenol (PNTP), and theantibody of the third nanocomposite is anti-insulin-like growth factor 1receptor antibody (anti-IGF-1). The Raman reporter molecule layer of thefourth nanocomposite comprises 4-(methylsulfanyl) thiophenol (4MSTP),and the antibody of the fourth nanocomposite is anti-Keratin 18antibody.

In one embodiment, SERS signal corresponding to each nanocomposite isrepresented by a predetermined color.

In one embodiment, the target of interest includes at least one tumorcell or at least one pathogen.

In certain embodiments, the nanocomposite further includes one or moremolecules of interest attached to the pegylated layer or the antibodylayer.

In one embodiment, the molecule of interest is a growth factor thatinduces certain biological functions, including the growth,proliferation of differentiation of cells or organisms.

In one embodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

In one embodiment, the nanocomposite further includes one or morefluorescent agents. The one or more fluorescent agents can be quantumdots or fluorescent dyes. The one or more fluorescent agents may bemixed with the Raman report molecules and located at the Raman reporterlayer, may be attached to or located at the antibody layer, or may beformed of a separate layer.

In another aspect, the present invention is directed to a nanocomposite.In one embodiment, the nanocomposite includes a core, a shellsurrounding the core, a reporter layer assembled on the shell,comprising a reporter molecule, and a targeting layer conjugated to thereporter layer, comprising targeting molecules.

In one embodiment, the core includes at least one gold nanorod, and theshell is a silver layer comprising silver nanoparticles.

In one embodiment, the reporter molecule layer is detectable by at leastone of surface enhanced Raman spectroscopy (SERS), magnetic resonanceimaging (MRI), x-ray radiography, computed tomography (CT), positronemission tomography-computed tomography (PET-CT), and infraredspectroscopy (IR).

In one embodiment, the reporter molecule comprises 4MBA, PATP, PNTP,4MSTP, or other molecules with unique Raman spectra and intense Ramanpeak intensities.

In one embodiment, the nanocomposite further includes a pegylated layerdisposed between the reporter layer and the targeting layer, and thepegylated layer has at least one of HS-PEG, HS-PEG-COOH and HS-PEG-NHx.

In one embodiment, the targeting molecules are molecules of anti-EpCAMantibody, anti-CD44 antibody, anti-IGF-1 antibody, or anti-Keratin 18antibody, or one or more antibodies specific to the target of interest.

In certain embodiments, the nanocomposite further includes one or moremolecules of interest attached to the pegylated layer or the antibodylayer.

In one embodiment, the molecule of interest is a growth factor thatinduces certain biological functions, including the growth,proliferation of differentiation of cells or organisms.

In one embodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

In one embodiment, the nanocomposite further includes one or morefluorescent agents. The one or more fluorescent agents can be quantumdots or fluorescent dyes. The one or more fluorescent agents may bemixed with the other report molecules and located at the reporter layer,may be attached to or located at the targeting layer, or may be formedof a separate layer.

In one embodiment, the present invention is directed to a nanoagentincluding at least one nanocomposite as described above, for detectingat least one tumor cell or at least one pathogen.

In a further aspect, the present invention is directed to a system fordetecting a target of interest. In certain embodiments, the systemincludes a nanoagent having at least one nanocomposite, a surfaceenhanced Raman spectrometer, and a processing unit. The nanocompositeincludes at least one gold nanorod, a silver layer coated on an outersurface of the gold nanorod and having silver nanoparticles, a Ramanreporter molecule layer assembled on the silver layer, a pegylated layercoated on the Raman reporter molecule layer and having at least one ofHS-PEG, HS-PEG-COOH and HS-PEG-NHx, and an antibody layer conjugated tothe pegylated layer and having molecules of an antibody. The surfaceenhanced Raman spectrometer is configured to provide an incidentradiation signal to the target of interest, and to collect SERS signalsgenerated by the Raman reporter molecule layer in response to theincident radiation signal. The processing unit is configured forprocessing the SERS signals collected by the surface enhanced Ramanspectrometer, so as to determine whether the target of interest has atleast one tumor cell or at least one pathogen.

In one embodiment, the at least one nanocomposite includes a firstnanocomposite, a second nanocomposite, a third nanocomposite, and afourth nanocomposite. The Raman reporter molecule layer of the firstnanocomposite includes 4MBA, and the antibody of the first nanocompositeis anti-EpCAM antibody. The Raman reporter molecule layer of the secondnanocomposite includes PATP, and the antibody of the secondnanocomposite is anti-CD44 antibody. The Raman reporter molecule layerof the third nanocomposite includes PNTP, and the antibody of the thirdnanocomposite is anti-IGF-1 antibody. The Raman reporter molecule layerof the fourth nanocomposite includes 4MSTP, and the antibody of thefourth nanocomposite is anti-Keratin 18 antibody.

In one embodiment, the SERS signals corresponding to the first, thesecond, the third, and the fourth nanocomposites are characterized withdifferent colors respectively.

In one embodiment, the nanorod has an AR in a range of about 1-9. In oneembodiment, the nanorod has the AR in the range of about 2-5. In oneembodiment, the nanorod has the AR in the range of about 2.77-3.23.

In one embodiment, the nanorod has a length in a range of about 10-100nm and has a diameter in a range of about 1-40 nm, respectively. In oneembodiment, the nanorod has the length in a range of about 35.20-36.80nm and has the diameter in a range of about 11.59-12.41 nm,respectively.

In one embodiment, the silver layer has a thickness in a range of about0.5-5 nm. In one embodiment, the silver layers have a thickness of about1-2 nm. In one embodiment, the silver layers have a thickness of about1.7 nm.

In one embodiment, the HS-PEG has a molecular weight in a range of about1.5-15 kilo Dalton (kD) and the HS-PEG-COOH has a molecular weight in arange of about 1-10 kD. In one embodiment, the HS-PEG has the molecularweight of about 5 kD and the HS-PEG-COOH has the molecular weight ofabout 3 kD.

In one embodiment, the at least one target includes at least one tumorcell or at least one pathogen.

In certain embodiments, the nanocomposite further includes one or moremolecules of interest attached to the pegylated layer or the antibodylayer.

In one embodiment, the molecule of interest is a growth factor thatinduces certain biological functions, including the growth,proliferation of differentiation of cells or organisms.

In one embodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

In one embodiment, the nanocomposite further includes one or morefluorescent agents. The one or more fluorescent agents may be quantumdots or fluorescent dyes. The one or more fluorescent agents may bemixed with the Raman report molecules and located at the Raman reporterlayer, may be attached to or located at the antibody layer, or may beformed of a separate layer.

In yet another aspect, the present invention is directed to a method ofmaking at least one nanocomposite for SERS detection of a target ofinterest. In certain embodiments, the method includes:

forming at least one gold nanorod;

coating a silver layer on an outer surface of the gold nanorod;

assembling a Raman reporter molecule layer on the coated silver layer,wherein the Raman reporter molecule layer includes Raman reportermolecules detectable by the SERS;

coating a thiolated polyethylene glycol (PEG) layer on the assembledRaman reporter molecule layer; and

conjugating the coated thiolated PEG layer with molecules of an antibodyto make the at least one nanocomposite.

In one embodiment, the step of forming the at least one gold nanorodincludes: mixing a first exadecyltrimethylammoniumbromide (CTAB)solution with a silver nitrate solution to form a first mixture;

adding a first HAuCl₄ to the first mixture to form a second mixture;

adding a first ascorbic acid to the second mixture to form a thirdmixture;

adding a seed solution to the third mixture to form a fourth mixture;and

centrifuging the fourth mixture to form a first precipitate, wherein thefirst precipitate comprises the gold nanorod.

In one embodiment, the seed solution is prepared by:

mixing a second CTAB solution with a second HAuCl₄ to form a fifthmixture; and

adding NaBH₄ to the fifth mixture and stirring to form the seedsolution.

In one embodiment, the step of coating the silver layer includes:

dispersing the gold nanorod in a third CTAB solution by sonication toform a sixth mixture;

adding a polyvinylpyrrolidone (PVP) solution and AgNO₃ to the sixthmixture and gently mixing to form a seventh mixture;

adding a second ascobic acid to the seventh mixture to form an eighthmixture;

adding NaOH solution to the eighth mixture to form a ninth mixture, suchthat the pH of the ninth mixture is elevated to about pH9, and a silverion reduction reaction is initiated; and

centrifuging the ninth mixture to form a second precipitate, wherein thesecond precipitate comprises gold nanorod coated with the silver layer.

In one embodiment, the step of assembling the Raman reporter moleculelayer includes:

dispersing the gold nanorod coated with the silver layer in distilledwater to form a tenth mixture;

dissolving the Raman reporter molecule selected from the groupconsisting of 4-MBA, PATP, PNTP, and 4-MSTP, in ethanol to form areporter solution;

adding the reporter solution to the tenth mixture and stirring for toform an eleventh mixture; and

centrifuging the eleventh mixture to form a third precipitate, whereinthe third precipitate comprises the gold nanorod coated with the silverlayer, and assembled with the Raman reporter molecule layer.

In one embodiment, the step of coating the thiolated PEG layer includes:

dispersing the gold nanorod with the coated silver layer and theassembled Raman report molecule layer in HS-PEG-COOH solution andvigorously stirring to form a twelfth mixture, wherein the HS-PEG-COOHsolution comprises about 2 mg/ml HS-PEG and about 2 mM NaCl;

adding HS-PEG to the twelfth mixture and keep at about 5° C. overnightto form a thirteenth mixture; and

centrifuging the thirteenth mixture to form a fourth precipitate,wherein the fourth precipitate comprises the gold nanorod coated withthe silver layer, assembled with the Raman reporter molecule layer, andcoated with the thiolated PEG layer.

In one embodiment, the step of conjugating the pegylated-Raman-silvercoated gold nanorod with an antibody includes:

suspending the gold nanorod coated with the silver layer, assembled withthe Raman reporter molecule layer, and coated with the thiolated PEGlayer in PBS buffer by sonicating to form a suspending mixture;

adding N-hydroxysuccinimide (NHS) and1N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) tothe suspending mixture and stirring to form a fourteenth mixture;

washing the fourteenth mixture by centrifuging twice using PBS buffer toobtain a fourth precipitate;

dispensing the fourth precipitate in PBS buffer to form a fifteenmixture;

adding the molecules of the antibody to the fifteenth mixture and mixingthoroughly to form a sixteen mixture, wherein the antibody includesanti-EpCAM, anti-CD44, anti-IGF-1 Receptor β, anti-Keratin 18, and oneor more antibodies specific to the target of interest; and

stirring the sixteenth mixture at room temperature to form thenanocomposite.

In one embodiment, SERS signal corresponding to each nanocomposite ischaracterized with a predetermined color.

In one embodiment, a method of making a nanoagent is provided, and thenanoagent includes one or more nanocomposite produced by the methoddescribed above.

In certain embodiments, the method further includes attaching one ormore molecules of interest to the pegylated layer or the antibody layer.

In one embodiment, the molecule of interest is a growth factor thatinduces certain biological functions, including the growth,proliferation of differentiation of cells or organisms.

In one embodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

In one embodiment, the method further includes attaching one or morefluorescent agents to the nanocomposite. The one or more fluorescentagents may be quantum dots or fluorescent dyes. The one or morefluorescent agents may be mixed with the Raman report molecules beforethe assemble step, so that the assembled Raman reporter molecule layercontains the one or more fluorescent agents. In other embodiments, theone or more fluorescent agents may also be attached to or located at theantibody layer, or may be formed of a separate layer.

Further areas of applicability of the invention will become apparentfrom the detailed description provided hereinafter. It should beunderstood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Patent and Trademark Officeupon request and payment of the necessary fee.

The following figures form part of the present specification and areincluded to further demonstrate certain aspects of the invention. Theinvention may be better understood by reference to one or more of thesefigures in combination with the detailed description of specificembodiments presented herein. The drawings described below are forillustration purposes only. The drawings are not intended to limit thescope of the present teachings in any way.

FIG. 1 schematically shows a nanocomposite of a nanoagent according toone embodiment of the invention.

FIG. 2A shows a flowchart of producing nanocomposites of a nanoagentaccording to one embodiment of the invention.

FIG. 2B schematically shows a process of producing nanocomposites of ananoagent according to one embodiment of the invention.

FIG. 3 shows images and diagrams of gold nanorods, silver coated goldnanorods, and nanocomposites according to certain embodiments of thepresent invention, where (A) shows HRTEM images of gold nanorods andsilver coated gold nanorods according to certain embodiments of thepresent invention; (B) shows SEM and STEM images of a silver coated goldnanorod according to one embodiment of the present invention; (C) showsUV-Visible spectra of gold nanorods and silver coated gold nanorodsaccording to one embodiment of the present invention; and (D) showsRaman signal intensity of gold nanorods, silver coated gold nanorods andnanocomposites having 4MBA according to one embodiment of the presentinvention.

FIG. 4 schematically shows diagrams of preparing and using differenttypes of SERS nanocomposites for cancer cells detection according tocertain embodiments of the invention, where (A) shows a schematicdiagram of preparing four types of SERS nanocomposites and the Ramanspectra (acquisition time 50 seconds) corresponding to each of the fourtypes of SERS nanocomposites according to one embodiment of the presentinvention; (B) shows schematically nanocomposites specifically targetingthe surface of a breast cancer cell to obtain the SERS thermal spectraaccording to one embodiment of the present invention; and (C) showsschematic views that different types of SERS nanocomposites accumulateon the surface of breast cancer cells (MCF-7) and produce multi-colorspectra according to one embodiment of the present invention.

FIG. 5A shows SEM images with EDS elemental analysis of nanocompositeson the MCF-7 cell surface according to one embodiment of the presentinvention.

FIG. 5B shows TEM images of nanocomposites cluster on the surface of anMCF-7 cell according to one embodiment of the present invention.

FIG. 6 shows the immunocytochemistry staining (ICC) of MCF-7 cells inmixed culture with fibroblast cells BJ-1 according to one embodiment ofthe present invention.

FIG. 7A shows Raman mapping images of cells according to certainembodiments of the present invention, where (a1) shows Raman mappingimages for targeting a single MCF-7 cancer cell among fibroblast cellswith four different SERS nanoagents; (a2) shows Raman mapping images ofa cancer cell without using any SERS nanoagents; and (a3) shows Ramanmapping images of a fibroblast cell (normal cell) with four SERSnanoagents.

FIG. 7B shows Raman mapping images of cells according to certainembodiments of the present invention, where (b1) shows Raman mappingimages of a single cancer cell, MCF-7, among millions of white bloodcells, using a nanoagent having four types of nanocomposites; (b2) showsRaman mapping images of a single cancer cell, MCF-7, among millions ofwhole blood cells, using a nanoagent having four types ofnanocomposites; and (b3) shows SERS mapping signal collected from thewhite blood cells only, i.e., without presence of cancer cells, using ananoagent having four types of nanocomposites.

FIG. 7C shows SERS signal collected with different time periods from 1second(s) to 5s, using a nanoagent having four types of nanocompositesaccording to one embodiment of the present invention.

FIG. 7D schematically shows SERS linear scanning position and SERSsignal of a selected single cancer cell according to one embodiment ofthe present invention, where (d1) shows SERS linear scanning position ofa selected single cancer cell, and (d2) shows SERS signal of a selectedsingle cancer cell scanned linearly four times along the line in (d1),each time with a specific scanning range corresponding to one of thefour types of SERS nanocomposites.

FIG. 8 shows images of SERS signal of a mixture of MCF-7 cell and whiteblood cells, using the negative nanocomposite having CD45, according tocertain embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likereference numerals refer to like elements throughout.

DEFINITIONS

The terms used in this specification generally have their ordinarymeanings in the art, within the context of the invention, and in thespecific context where each term is used. Certain terms that are used todescribe the invention are discussed below, or elsewhere in thespecification, to provide additional guidance to the practitionerregarding the description of the invention. For convenience, certainterms may be highlighted, for example using italics and/or quotationmarks. The use of highlighting and/or capital letters has no influenceon the scope and meaning of a term; the scope and meaning of a term arethe same, in the same context, whether or not it is highlighted and/orin capital letters. It will be appreciated that the same thing can besaid in more than one way. Consequently, alternative language andsynonyms may be used for any one or more of the terms discussed herein,nor is any special significance to be placed upon whether or not a termis elaborated or discussed herein. Synonyms for certain terms areprovided. A recital of one or more synonyms does not exclude the use ofother synonyms. The use of examples anywhere in this specification,including examples of any terms discussed herein, is illustrative onlyand in no way limits the scope and meaning of the invention or of anyexemplified term. Likewise, the invention is not limited to variousembodiments given in this specification.

It will be understood that when an element is referred to as being “on”another element, it can be directly on the other element or interveningelements may be present therebetween. In contrast, when an element isreferred to as being “directly on” another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed below canbe termed a second element, component, region, layer or section withoutdeparting from the teachings of the invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising”, or “includes” and/or “including” or “has” and/or“having” when used in this specification specify the presence of statedfeatures, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top”, may be used herein to describe one element's relationship toanother element as illustrated in the figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation shown in the figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on the “upper” sides of the other elements. The exemplary term“lower” can, therefore, encompass both an orientation of lower andupper, depending on the particular orientation of the figure. Similarly,if the device in one of the figures is turned over, elements describedas “below” or “beneath” other elements would then be oriented “above”the other elements. The exemplary terms “below” or “beneath” can,therefore, encompass both an orientation of above and below.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and theinvention, and will not be interpreted in an idealized or overly formalsense unless expressly so defined herein.

It will be understood that when an element is referred to as being “on”,“attached” to, “connected” to, “coupled” with, “contacting”, etc.,another element, it can be directly on, attached to, connected to,coupled with or contacting the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being,for example, “directly on”, “directly attached” to, “directly connected”to, “directly coupled” with or “directly contacting” another element,there are no intervening elements present. It will also be appreciatedby those of skill in the art that references to a structure or featurethat is disposed “adjacent” to another feature may have portions thatoverlap or underlie the adjacent feature.

As used herein, “around”, “about”, “substantially” or “approximately”shall generally mean within 20 percent, preferably within 10 percent,and more preferably within 5 percent of a given value or range.Numerical quantities given herein are approximate, meaning that theterms “around”, “about”, “substantially” or “approximately” can beinferred if not expressly stated.

As used herein, the terms “comprise” or “comprising”, “include” or“including”, “carry” or “carrying”, “has/have” or “having”, “contain” or“containing”, “involve” or “involving” and the like are to be understoodto be open-ended, i.e., to mean including but not limited to.

As used herein, the term “MCF-7” refers to a breast cancer cell lineisolated in 1970 from a 69-year-old Caucasian woman. MCF-7 is theacronym of Michigan Cancer Foundation-7, referring to the institute inDetroit where the cell line was established in 1973 by Herbert Soule andco-workers. The Michigan Cancer Foundation is now known as the BarbaraAnn Karmanos Cancer Institute. Prior to MCF-7, it was not possible forcancer researchers to obtain a mammary cell line that was capable ofliving longer than a few months. The patient, whose name, FrancesMallon, is unknown to the vast majority of cancer researchers, died in1970. Her cells were the source of much of current knowledge aboutbreast cancer. At the time of sampling, she was a nun in the convent ofImmaculate Heart of Mary in Monroe, Mich. under the name of SisterCatherine Frances. MCF-7 and two other breast cancer cell lines, namedT-47D and MDA-MB-231, account for more than two-thirds of all abstractsreporting studies on mentioned breast cancer cell lines, as concludedfrom a Medline-based survey.

As used herein, the term “BJ-1 cell line” refers to a normal skinfibroblast cell line, which is available from American Type CultureCollection (ATCC) with ATCC number CRL-2522.

As used herein, the term “circulating tumor cells” or “CTCs” refers tocells that have shed into the vasculature from a primary tumor andcirculate in the bloodstream. CTCs thus constitute seeds for subsequentgrowth of additional tumors (metastasis) in vital distant organs,triggering a mechanism that is responsible for the vast majority ofcancer-related deaths.

As used herein, the term “DMEM” refers to Dulbecco's Modified EagleMedium, and EMEM is the abbreviation of Eagle's Minimum EssentialMedium.

As used herein, the term “ICC” refers to the abbreviation ofimmunocytochemistry staining.

As used herein, the term “4MBA” refers to 4-mercaptobaezoic acid, PNTPis the abbreviation of p-nitrobenzoic acid, PATP is the abbreviation ofp-aminobenzoic acid, 4MSTP is the abbreviation of 4-methylsulfanylthiophenol, and 4APDS is the abbreviation of 4-aminophenyldisulfide.

As used herein, the term “HS-PEG-COOH and HS-PEG” refer to thiolatedpolyethylene glycol with or without acid terminal, respectively.

As used herein, the term “phosphate buffered saline” or “PBS” refers toa buffer solution commonly used in biological research. It is awater-based salt solution containing sodium phosphate, sodium chlorideand, in some formulations, potassium chloride and potassium phosphate.The osmolarity and ion concentrations of the solutions match those ofthe human body (isotonic).

As used herein, the term “bovine serum albumin” or “BSA” or “Fraction V”refers to a serum albumin protein derived from cows. It is often used asa protein concentration standard in lab experiments.

As used herein, the term “fetal bovine serum” or “FBS” or “fetal calfserum” refers to the blood fraction remaining after the naturalcoagulation of blood, followed by centrifugation to remove any remainingred blood cells. Fetal bovine serum comes from the blood drawn from abovine fetus via a closed system of collection at the slaughterhouse.Fetal bovine serum is the most widely used serum-supplement for the invitro cell culture of eukaryotic cells. This is due to it having a verylow level of antibodies and containing more growth factors, allowing forversatility in many different cell culture applications.

OVERVIEW OF THE INVENTION

The conjugation of the nanomaterials with targeting molecules such asantibodies, folates, aptamer or immune protein could provide specificdelivery of the nanomaterials to various cancer cell lines, withinminutes [3-8]. Recently, quantum dot nanomaterials and iron oxidenanoparticles have been used widely as imaging and diagnostic nanoagentsfor cancer cells [16-18]. Among these new and enhanced imaging anddiagnostic assays, surface-enhanced Raman spectroscopy (SERS) has beenstudied and proposed for early imaging and detection [19-22] of tumorcells.

In one aspect, the present invention is directed to a biocompatiblenanoagent for detecting a target of interest by SERS. In certainembodiments, the target may include at least one tumor cell or at leastone pathogen. The tumor cell can be a benign tumor cell or a malignanttumor cell. The malignant tumor cell, or a cancer cell, can be locatedlocally or a circulating tumor cell (CTC). The pathogen can be a virus,bacterium, prion, fungus or protozoan that causes disease in its host.In certain embodiments, the nanoagent includes at least onenanocomposite, such as four different types of nanocomposites.

In one embodiment, the nanocomposite includes at least one gold nanorod,a silver layer coated on an outer surface of the gold nanorod and havingsilver nanoparticles, a Raman reporter molecule layer coated on thesilver layer and having Raman reporter molecules, a pegylated layercoated on the Raman reporter molecule layer and having at least one ofthiolated polyethylene glycol (HS-PEG), thiolated polyethylene glycolacid (HS-PEG-COOH) and HS-PEG-NHx, and an antibody layer conjugated tothe pegylated layer and having molecules of an antibody. In oneembodiment, the AR of the gold nanorod is in a range of 2-5. In oneembodiment, the AR of the gold nanorod is in a range of 2.77-3.23 or isabout 3±0.23, and the length and the diameter of the gold nanorod is ina range of about 35.20-36.80 and about 11.59-12.41 respectively, orabout 36±0.80 nm and about 12±0.41 nm, respectively, and the thicknessof the silver layer is about 1-2 nm, or about 1.7 nm.

In one embodiment, the at least one nanocomposite includes a firstnanocomposite, a second nanocomposite, a third nanocomposite, and afourth nanocomposite. The Raman reporter molecule layer of the firstnanocomposite includes 4-mercaptobenzoic acid (4MBA), and the antibodyof the first nanocomposite is anti-epithelial cell adhesion moleculeantibody (anti-EpCAM). The Raman reporter molecule layer of the secondnanocomposite includes p-aminothiophenol (PATP), and the antibody of thesecond nanocomposite is anti-CD44 antibody. The Raman reporter moleculelayer of the third nanocomposite includes p-nitrothiophenol (PNTP), andthe antibody of the third nanocomposite is anti-insulin-like growthfactor 1 receptor antibody (anti-IGF-1). The Raman reporter moleculelayer of the fourth nanocomposite includes 4-(methylsulfanyl) thiophenol(4MSTP), and the antibody of the fourth nanocomposite is anti-Keratin 18antibody.

In one embodiment, SERS signal corresponding to each nanocomposite isrepresented by a predetermined color, such that SERS signals of thenanoagent having multiple nanocomposites are represented by multiplecolors.

In another aspect, the present invention is directed to a system fordetecting a target of interest. In certain embodiments, the target ofinterest includes at least one tumor cell or at least one pathogen. Incertain embodiments, the system includes a nanoagent as described abovethat has multiple nanocomposites, a surface enhanced Raman spectrometerconfigured to provide an incident radiation signal to the target ofinterest, and to collect surface enhanced Raman spectroscopy (SERS)signals generated by the Raman reporter molecule layer in response tothe incident radiation signal, and a processing unit for processing theSERS signals collected by the surface enhanced Raman spectrometer todetermine whether the target of interest have at least one tumor cell orat least one pathogen.

In a further aspect, the present invention is directed to a method ofmaking a nanocomposite or a nanoagent having one or more nanocomposites,where the nanocomposite/nanocomposites have the structures as describedabove, and the nanocomposite/nanoagent can be used for surface enhancedRaman spectroscopy (SERS) detection of a target of interest, such as atleast one tumor cell or at least one pathogen.

In one embodiment, the method includes: forming a gold nanorod, coatinga silver layer on an outer surface of the gold nanorod; assembling aRaman reporter molecule layer on the coated silver layer, wherein theRaman reporter molecule layer includes Raman reporter molecules that aredetectable by the SERS; coating a thiolated polyethylene glycol (PEG)layer on the assembled Raman reporter molecule layer; and conjugatingthe coated thiolated PEG layer with molecules of an antibody to make thenanocomposite.

Anti-EpCam antibody, anti-CD44 antibody, anti-keratin 18 antibody,anti-IGF-I antibody, and one or more antibodies specific to the targetof interest are used in the present invention.

Since the epithelial cell adhesion molecule (EpCam) antigen is highlyexpressed in normal epithelial cells and the MCF-7 cells originatingfrom these cells, the cells express a considerable amount of EpCamantigen on their surface. Because the EpCam antigen is greatlyover-expressed in many types of cancers, including colon, hepatic,pancreatic, prostate, and breast cancer [32], Anti-EpCam has been usedextensively in breast cancer detection.

CD44 is a cell-cell and cell-matrix adhesion molecule known to be highlyexpressed in many types of cancers and widely used in the diagnosis andprognosis of breast cancer [33, 34]. CD44 is important in tumordevelopment and progression, and anti-CD44 provides multiple prospectsfor advanced cancer treatments by targeting therapeutics to the CD44receptor of the metastasizing tumors, interfering with the CD44signaling pathway.

Keratin 18 is known to be highly expressed in normal mammary epithelialcells, and MCF-7 cells are adenocarcinoma derived from simple breastepithelium. In one embodiment, anti-keratin 18 antibodies have been usedin diagnostic histopathology of breast cancer. In addition, it has beenshown that the down-regulation of membrane keratin 18 plays a key rolein the prognosis of the breast cancer patient [35].

Insulin-like growth factor 1 (IGF-I) is expressed in 90% of breastcancer specimens. Therefore, the anti-IGF-I antibody is used as anmolecule to target breast cancer cells [36, 37].

These and other aspects of the invention are more specifically describedbelow.

Implementations and Examples of the Invention

Without intend to limit the scope of the invention, further exemplaryprocedures and preliminary experimental results of the same according tothe embodiments of the invention are given below.

In one aspect, the present invention is directed to a biocompatiblenanoagent for detecting a target of interest, such as at least onecancer cell or at least one pathogen, by SERS. In certain embodiments,the biocompatible nanoagent includes one or more nanocomposites.

FIG. 1 schematically shows a nanocomposite of a nanoagent according toone embodiment of the invention. Referring to FIG. 1, each of thenanocomposite 100 includes a core 102, a shell 106 wrapped around thecore 102, a reporter layer 110 assembled on the shell 106, a bindinglayer 114 coated on the reporter layer 110, and a targeting layer 118conjugated to the binding layer 114.

In certain embodiments, the core 102 is a gold nanorod (AuNR). Theaspect ratio (AR) is defined as the ratio of the length of the AuNR tothe diameter of the AuNR. In one embodiment, the AR of the AuNR 102 maybe in the range of about 0.3-30, and the length and diameter of the AuNR102 may be in the range of about 3.6-360 nanometer (nm) and about1.2-120 nm, respectively. In one embodiment, the AR of the AuNR 102 isin the range of about 1-9. In one embodiment, the precise AR of the AuNR102 is in the range of about 2-5. In one embodiment, the precise AR ofthe AuNR 102 is in the range of about 2.77-3.23, or about 3±0.23. In oneembodiment, the length and diameter of the AuNR 102 may be in the rangeof about 10-100 nm and about 1-40 nm, respectively. In one embodiment,the particle length and diameter of the AuNR 102 may be approximately36±0.80 nm and 12±0.41 nm, respectively. In one embodiment, these twodimensions are adequate to form two kinds of surface plasmon modes: aweak one around 520 nm transvers mode, and a very strong longitudinalplasmon around 766 nm [26]. The longitudinal surface plasmon is crucial,and the maximum excitation of this strong surface plasmon mode can beachieved when excited by a Raman excitation laser at about 784 nm. Thisensures ultimate sensitivity and very low detection limits when usesSERS for cancer cell detection.

In one embodiment, the shell 106 is a silver layer. The silver layer 106is coated on the AuNR 102 to form a silver coated gold nanorod(AuNR/Ag). In one embodiment, the AuNR 102 and the silver layer 106 haverough surfaces.

In one embodiment, the thickness of the silver layer 106 may be in therange of about 0.2-20 nm. In one embodiment, the thickness of the silverlayer 106 is In the range of about 0.5-5 nm. In one embodiment, thethickness of the silver layer 106 is about 1-2 nm. In one embodiment,the thickness of the silver layer 106 is about 1.7 nm. The thin silverlayer 106 helps maintain the longitudinal surface plasmon wavelength asclose as possible to the excitation laser source (784 nm), in order toachieve the maximum SERS signal. Any thick silver coating will changethe surface plasmon significantly [30].

In one embodiment, the reporter layer 110 is a Raman reporter moleculelayer having Raman reporter molecules. In one embodiment, the Ramanreporter molecules are thiolated organic molecules absorbed on thesurface of the AuNR/Ag. In one embodiment, the Raman reporter moleculemay be at least one of 4-mercaptobenzoic acid (4MBA), p-aminothiophenol(PATP), p-nitrothiophenol (PNTP), 4-(methylsulfanyl) thiophenol (4MSTP),and other molecules with unique Raman spectra and intense Raman peakintensities. In other words, the one or more nanocomposites 100 of thenanoagent may include at least one of the following four types ofnanocomposites: a nanocomposite having a 4MBA reporter layer, ananocomposite having a PATP reporter layer, a nanocomposite having aPNTP reporter layer, and a nanocomposite having a 4MSTP reporter layer.In certain embodiments, the nanoagent may include all of these fourtypes of nanocomposites 100. All the SER Raman spectra are obtainedthrough the detection of those Raman reporter molecules.

In the above embodiment, the reporter molecule is a Raman reportermolecule. In certain embodiments, the reporter layer 110 may includeother type of reporter molecules such that the produced nanoagent may beused together with detecting methods other than SERS, such as MRI, x-rayradiography, CT or IR. In certain embodiments, the reporter molecule isdetectable by different methods. In certain embodiments, the reportmolecules may include one or more fluorescent agents. The one or morefluorescent agents can be quantum dots or fluorescent dyes.

In the above embodiment, the nanoagent includes at least one of the fourtypes of nanocomposites corresponding to four types of reportermolecules. In certain embodiments, the nanoagent may include all fourtypes of nanocomposites. In certain embodiments, the nanoagent mayinclude one, two, three, or more than four types of nanocomposites, andeach type of nanocomposite has a special type of reporter molecule. Inother embodiments, one type of nanocomposite may include two or moredifferent types of reporter molecules. In certain embodiments, one typeof nanocomposite may also include two, three, four or more types ofreporter molecules.

In one embodiment, the binding layer 114 is applied to the surface ofthe SERS reporter molecule coated AuNR/Ag. In one embodiment, thebinding layer 114 is a pegylated layer. In one embodiment, the pegylatedlayer may include thiolated PEG polymers, for example, at least one ofHS-PEG, HS-PEG-COOH and HS-PEG-NHx, which are suitable for being used asSERS tags and are non-toxic. Additionally, the thiolated PEG polymers donot displace Raman reporter molecules, which attach to the surface ofgold nanoparticles [40]. In certain embodiments, the x in the HS-PEG-NHxis a positive integer. In one embodiment, x is 1 or 2.

In one embodiment, the pegylated layer 114 includes a mixture of HS-PEGand HS-PEG-COOH, which serves as protective, bio-dispersive and linkerto the later conjugated antibodies. In one embodiment, the averagemolecular weight of the HS-PEG is about 5 kD, and the average molecularweight of the HS-PEG-COOH is about 3 kD. In one embodiment, each nanorod(SERS reporter molecule coated AuNR/Ag) requires about 4,200 moleculesto assure complete surface coverage, i.e. each HS-PEG molecule required0.35 nm² footprint [39]. The pegylated layer 114 may achieve at leasttwo purposes. First, the pegylated layer 114 protects the nanorodssurface and makes the nanocomposite more hydrophilic, and easilydisperses the nanocomposite in aqueous medium, for example, biologicalfluids. Second, the pegylated layer 114 provides a carboxylic terminalon the surface of the SERS reporter molecule coated AuNR/Ag, which isthe linker between the SERS reporter molecule coated AuNR/Ag surface andthe antibodies that will attached thereon for targeting the target, suchas cancer cells.

In certain embodiments, the targeting layer 118 is an antibody layer.The antibody layer 118 includes molecules of a type of antibody whichspecifically targeting certain cancer cell surface antigen. In oneembodiment, the antibody is attached covalently to HS-PEG-COOH (—COOHterminal) and plays a role in the specific SERS nanocomposite deliveryto the cancer cells.

In one embodiment, the antibody layer 118 may include molecules of atleast one of an anti-EpCAM antibody, an anti-CD44 antibody, ananti-IGF-1 Receptor β antibody, an anti-Keratin 18 antibody, and one ormore antibodies specific to the target of interest. In other words, theone or more nanocomposites 100 of the nanoagent may include at least oneof the following four types of nanocomposites: the nanocomposite havingan anti-EpCAM antibody layer, the nanocomposite having an anti-CD44antibody layer, the nanocomposite having an anti-IGF-1 Receptor βantibody layer, and the nanocomposite having an anti-keratin 18 antibodylayer. In one embodiment, the biocompatible nanoagent having at leastone of the four types of nanocomposites may be used for detecting andimaging breast cancer cells, for example, MCF-7, and allow for thecapability to distinguish one single cancer cells among normal cells. Inone embodiment, the biocompatible nanoagent includes all four types ofnanocomposites.

In the above embodiment, the targeting layer 118 includes antibodies. Incertain embodiments, the targeting layer 118 may include other type oftargeting molecules to specifically binding an object, for example, aligand that can bind a receptor, or a lectin that can bind acarbohydrate.

In certain embodiments, the nanocomposite may further include one ormore molecules of interest attached to the binding layer 114 or thetargeting layer 118. In one embodiment, the molecule of interest is agrowth factor that induces certain biological functions, including thegrowth, proliferation of differentiation of cells or organisms. In oneembodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

In the above embodiment, the nanoagent may include at least one of thefour types of nanocomposites corresponding to four types of reportermolecules. In certain embodiments, the nanoagent may include all fourtypes of nanocomposites. In certain embodiments, the nanoagent mayinclude one, two, three, or more than four types of nanocomposites, andeach type of nanocomposite has a special type of reporter molecule. Inother embodiments, one type of nanocomposite may include two or moredifferent types of reporter molecules.

In the above embodiment, the nanoagent includes at least one of the fourtypes of nanocomposites corresponding to four types of antibodies. Incertain embodiments, the nanoagent may include all four types ofnanocomposites. In certain embodiments, the nanoagent may include one,two, three, or more than four types of nanocomposites, and each type ofnanocomposite has a specific type of antibody. In other embodiments, onetype of nanocomposite may include two or more different types ofantibodies.

In one embodiment, the nanoagent as described above can be used todetect at least one tumor cell or at least one pathogen by SERS. In oneembodiment, the tumor cell is a circulating tumor cell.

In certain embodiments, the nanocomposite of the nanoagent may furtherinclude one or more molecules of interest attached to the nanocomposite.In one embodiment, the molecule of interest is a growth factor thatinduces certain biological functions, including the growth,proliferation of differentiation of cells or organisms. In oneembodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

In other embodiments, the nanoagent is configured to detect a target ofinterest other than at least one tumor cell, or configured to be usedwith methods other than SERS. In one embodiment, the nanoagent isconfigured to detect a specific type of cell, for example a cancer cell,a blood and immune system cell, a hormone secreting cell, or any othercells that express a specific antigen or certain cell surface molecules.In one embodiment, the nanoagent is configured to detect a pathogen, forexample a bacteria, a fungus or a virus. In one embodiment, thenanoagent is configured to detect an exogenous chemical or device thatis applied to a patient. In one embodiment, the detection using thenanoagent can be performed in vivo or in vitro.

In one embodiment, the nanoagent includes Raman reporter molecules thatare detectable by SERS. In certain embodiment, the nanoagent may includereporter molecules detectable by methods other than SERS, such as MRI,x-ray radiography, CT, or IR. The nanoagent is therefore configured tobe applied with methods other than SERS, for specific targeting,detection, and treatment of cancer cells or other targeted cells,tissues or objects. In certain embodiments, the reporter molecules aredetectable by two, three, four or more different methods describedabove. In certain embodiments, the report molecules may include one ormore fluorescent agents. The one or more fluorescent agents can bequantum dots or fluorescent dyes.

In another aspect, the present invention is directed to a process formaking a biocompatible nanoagent 200. In certain embodiments, thebiocompatible nanoagent 200 may have the structure as shown in FIG. 1.

FIG. 2A shows a flowchart of producing nanocomposites of a nanoagentaccording to one embodiment of the invention. FIG. 2B schematicallyshows a process of producing nanocomposites of a nanoagent according toone embodiment of the invention. Referring to FIGS. 2A and 2B, theprocess of producing nanocomposites includes a plurality of operations.At operation 252, a core (e.g., the AuNR 202) is formed. At operation256, a shell layer (e.g., the silver layer 206) is wrapped around thecore (e.g., the AuNR 202) to form the AuNR/Ag. At operation 260, areporter layer 210 (e.g., M1, M2, M3 or M4) is assembled or coated onthe surface of the shell layer (e.g., the silver layer 206). Atoperation 264, a binding layer 214 (e.g., the pegylated layer) is coatedon the reporter layer 210, and at operation 268, a targeting layer 218(e.g., the antibody layer) is attached on the binding layer 214.

As discussed above, the core 202 being prepared in operation 252 may bethe AuNR. In one embodiment, the AuNR 202 with tuned size is preparedaccording to the seed mediated method by Nikoobakht [26]. Specifically,5 ml of 0.2 M hexadecyltrimethylammoniumbromide (CTAB) solution is mixedwith 5 ml of 0.0005 M HAuCl₄, and then 600 μl of NaBH₄ is added to themixture with stirring for about two minutes, to form a seed solution. Tosynthesize AuNRs with an aspect ratio around 3, 5 ml of 0.2 M CTAB ismixed with 150 μl of 0.004 M silver nitrate solution to form a firstmixture. Then, 5 ml of 0.001 M HAuCl₄ is added to and mixed with thefirst mixture to form a second mixture. After that, 70 μl of 0.0788 Mascorbic acid is mixed with the second mixture to form a third mixture.Finally, 12 μl of the prepared seed solution is added to the thirdmixture to form a fourth mixture. The fourth mixture is kept at 30° C.for about 40 minutes without any further stirring to form the AuNRs.

FIG. 3 (A) shows HRTEM images of gold nanorods and silver coated goldnanorods according to certain embodiments of the present invention, andFIG. 3 (C) shows UV-Visible spectra of gold nanorods and silver coatedgold nanorods according to one embodiment of the present invention. Asshown by HRTEM images of (a1) and (a2) of FIG. 3 (A), the particlelength and diameter of the AuNRs are approximately 36±0.80 nm and12±0.41 nm, respectively. As shown in FIG. 3 (C), these two dimensionsare adequate to form two kinds of surface plasmon modes: a weak onearound 520 nm transvers mode, and a very strong longitudinal plasmonaround 766 nm [26]. As discussed above, the longitudinal surface plasmonis crucial, where the maximum excitation of this strong surface plasmonmode with the excitation by a Raman excitation laser at 784 nm can beachieved. This ensured achieving ultimate sensitivity and very lowdetection limits.

As discussed above, the silver layer 206 is coated on the AuNR 202 inoperation 256 to form a silver coated gold nanorod (AuNR/Ag). In certainembodiments, the prepared AuNRs are covered with a thin (>1 nm) silverlayer, using the reported method [30, 34], which are incorporated byreference in their entireties. Specifically, the AuNRs formed by theoperation 252 are purified by centrifugation (10,000 rpm, 30 min) twiceto remove any excess reagents, using an ultracentrifuge (ThermoScientific, Sorvall RC6+) with the rotor F215-8X50Y. The precipitate isre-dispersed in 5 ml CTAB solution by sonication. Then, 5 ml of 1% PVPsolution and 250 μl of 0.001 M AgNO₃ are added to the AuNRs solutionwith gentle mixing. After that, 100 μl of 0.1 M ascorbic acid is addedand 200 μl of NaOH solution is added to elevate the pH to around 9, inorder to initiate the silver ion reduction reaction, such that silvercoated gold nanorods are formed.

As discussed above, the thin silver layer 106 helps maintain thelongitudinal surface plasmon wavelength as close as possible to theexcitation laser source (784 nm), in order to achieve the maximum SERSsignal. As shown by HRTEM images of (a3) to (a5) of FIG. 3A, thethickness of the silver layer 206 is about 1.7 nm. Any thick silvercoating will change the surface plasmon significantly [30]. FIG. 3(D)shows Raman signal intensity of gold nanorods, silver coated goldnanorods and nanocomposites having 4MBA according to one embodiment ofthe present invention. Specifically, FIG. 3(D) shows role of silverlayer in SERS Raman enhancing (acquisition time 10s). As shown in FIG.3(D), the silver layer 106 enhances the SERS Raman signal of AuNR/Ag bya factor of at least 129 times compared to that of pure AuNR. Thecalculation of the enhancement factor was done by analyzing the Ramanintensity of the same peaks when the Raman molecule (4MBA) was depositedon the gold nanorods and on the AuNR/Ag nanostructures, as shown in FIG.3D.

FIG. 3(B) shows SEM and STEM images of a silver coated gold nanorodaccording to one embodiment of the present invention. As shown in FIG.3(B), (b1) is a SEM image of a AuNR/Ag, (b2) is a STEM gold EDS elementimage of the AuNR/Ag, (b3) is a STEM silver EDS layer element image ofthe AuNR/Ag, (b4) is a STEM overlapped image of the AuNR/Ag, and (b5) isa EDS cross-scanning spectra of the AuNR/Ag.

Referring back to FIG. 3(C), the silver layer epitaxial growth on thegold nanorod surface can be confirmed by the absorbance spectra. Uponthe silver layer growth, the longitudinal band of gold nanorods showed ablue shift of around 20 nm (to about 740 nm), and there were nosignificant silver band appeared in the lower wavelength, which supposesto appear in that range if the silver completely covered the goldnanorods. This result is consistent with the HRTEM images that a verythin layer of silver has formed on the gold nanorod surface. The thinsilver layer 206 helps maintain the longitudinal surface plasmonwavelength as close as possible to the excitation laser source (784 nm),in order to achieve the maximum SERS signal. Any thick silver coatingwill change the surface Plasmon significantly [30]. Further, theinserted figure in FIG. 3 (C) shows the UV-Visible spectra of four typesof nanocomposites having Anti-EpCam antibody, anti-CD44 antibody,anti-keratin 18 antibody, anti-IGF-I antibody, and a negative controlnanocomposite having anti-CD45 antibody, according to one embodiment ofthe present invention. As shown in the inserted UV-Visible spectra,after the bioconjugation of the different types of antibodies on thesurface of the silver-gold nanorod, there was still strong absorption inthe UV-Visible spectra for both longitudinal and transversal absorbance.

As discussed above, the reporter layer 210 is coated on the silver layer206 in operation 260. In certain embodiments, the reporter layer 210 maybe a Raman reporter molecule layer, and the Raman reporter molecules maybe thiolated organic molecules absorbed on the surface of the AuNR/Ag.The thiolated Raman reporter molecules are more easily assembled on thesilver surface rather than gold [38] by forming Ag—S covalent bondwithin a short period of time, for example about 3 hours, and atmoderate temperature, for example ≧45° C. In certain embodiments,different reporter molecules or marker molecules may be used. TheAuNR/Ag assembled with reporter or marker molecules can be named, M₁,M₂, M₃, . . . M_(n), respectively, which includes the different reporteror marker molecules, where n is a positive integer. Specifically, thesilver coated gold nanorods (AuNR/Ag) obtained in the operation 256 maybe purified by centrifugation at 12,000 rpm and redispersed in deionized(DI) water. The centrifugation may be repeated at least once to removeany excess reagents. Then thiophenol molecules can be self-assembled onthe surface of silver layer [45]. In one example, five thiophenolderivatives are prepared with 10 mM each ethanol based solution, in fiveseparate conical flasks each contain 5 ml of AuNR/Ag. Then 5 μl of oneof 4MBA, PATP, PNTP, 4MSTP, and 4ADPS is added and kept under stirringfor about 3 hours with 45° C. to assure that a large portion of surfaceattached CTAB are replaced by Raman SERS molecules. Unabsorbed excesswas removed by centrifugation once at 10,000 rpm for 30 min.

As described above, in order to reduce the risks of false results thatmay raise from using single SERS nanocomposite (one Raman peak signal),multiple SERS nanocomposites can be simultaneously prepared to have aseries of discriminated peaks each corresponds to a specific SERSnanocomposite.

FIG. 4 schematically shows diagrams of preparing and using differenttypes of SERS nanocomposites for cancer cells detection according tocertain embodiments of the invention. Specifically, FIG. 4 (A) shows aschematic diagram of preparing four types of SERS nanocomposites and theRaman spectra (acquisition time 50 seconds) corresponding to each of thefour types of SERS nanocomposites according to one embodiment of thepresent invention. Referring to FIG. 4 (A), schematic diagram ofpreparing four types of SERS nanocomposites and the Raman spectra(acquisition time 50s) corresponding to each of the four types of SERSnanocomposites are provided. Each color represents a unique AuNR/Agcovered by small organic compounds then a layer of HS-PEG-COOH and thena specific cancer cell antibody layer, where the blue color representsAuNR/Ag/4MBA/anti-EpCAM, the red color representsAuNR/Ag/PNTP/anti-IGF-1 Receptorβ, the green color representsAuNR/Ag/PATP/anti-CD44, and the magenta color-representsAuNR/Ag/4MSTP/anti-Keratin18. The nanocomposites containing 4MBA shows aspecific peak at 422 cm⁻¹, the nanocomposites containing PATP shows aspecific peak at 1372 cm⁻¹, the nanocomposites containing PNTP shows aspecific peak at 1312 cm⁻¹, and the nanocomposites containing 4MSTPshows a specific peak at 733 cm⁻¹. Thus, in one embodiment, fourdifferent SERS signals are completely separated and do not have anyoverlapping peaks.

FIG. 4 (B) shows schematically nanocomposites specifically targeting thesurface of a breast cancer cell to obtain the SERS thermal spectraaccording to one embodiment of the present invention.

FIG. 4 (C) shows schematic views that different types of SERSnanocomposites accumulate on the surface of breast cancer cells (MCF-7)and produce multi-color spectra according to one embodiment of thepresent invention.

As described above, in one embodiment, the Raman reporter molecule is atleast one of 4MBA, PATP, PNTP, 4MSTP, and other molecules with uniqueRaman spectra and intense Raman peak intensities. In one embodiment, theproduced nanocomposites include at least one of a nanocomposite having a4MBA layer, a nanocomposite having a PATP layer, a nanocomposite havinga PNTP layer, and a nanocomposite having a 4MSTP layer. All the SERRaman spectra are obtained through the detection of those Raman reportermolecules. In this way, Raman reporter molecules can be attached on thethin silver surface, while the silver coated gold nanorod still keepsthe high SERS signal enhancement. For example, when the Raman reportermolecule is 4MBA, the 4MBA attached silver coated gold rod shows sixtimes more enhancement than Raman signal in the related art.

In certain embodiments, the reporter molecules are suitable for beingdetected by methods other than SERS, and the biocompatible agent havingone or more nanocomposites are therefore configured to be applied withmethods other than SER, for specific targeting, detection, and treatmentof cancer cells or other targeted objects. In one embodiment, the reportmolecules may include one or more fluorescent agents, and the one ormore fluorescent agents may be quantum dots or fluorescent dyes.

In operation 264, the binding layer 214 is coated on the reporter layer210. In one embodiment, the binding layer 214 is a pegylated layer. Inone embodiment, the pegylated layer 214 includes a mixture of HS-PEG andHS-PEG-COOH, which serves as protective, bio-dispersive and linker tothe conjugated antibodies. Specifically, one of the precipitates fromthe previous step is redispersed in 2 ml HS-PEG-COOH (MW˜3000) solution(2 mg/ml in 2 mM NaCl), and vigorously stirred for 15 min. Then, 1.8 mlof HS-PEG solution (2 mg/ml in 2 mM NaCl) is added and kept in contactwith the SERS nanoagents at 5° C. overnight. After that, the unboundthiolated PEG is removed by centrifugation at 4000 rpm for 15 min andredispersed using probe sonication twice. The precipitate for eachcoated nanorod solution is then re-suspended in 1×PBS (phosphate buffersolution) solution.

As described above, to stabilize the prepared SERS nanocomposites, athin layer of HS-PEG(5 kD)/HS-PEG-COOH(3 kD) mixture are used, eachnanorod required around 4,200 molecules to assure complete surfacecoverage, i.e. each HS-PEG molecule requires 0.35 nm² footprint [39].This layer has to serve two purposes: first, to protect the nanorodssurface and to make the SERS nanoagents more hydrophilic and easilydisperse in aqueous medium like biological fluids, and second to providea carboxylic terminal on the surface of the SERS nanoagent, which is thelinker between the nanorod surface and the antibodies that will usedlater for targeting cancer cells. Thiolated PEG polymers are widely usedwith SERS tags and are well known as non-toxic; additionally, they donot displace Raman reporter molecules, which attach to the surface ofgold nanoparticles [40].

In operation 268, a targeting layer 218 is attached on the binding layer214, so as to form the nanocomposites. The formed nanocomposites mayinclude different antibodies, and can be named correspondingly as AB₁,AB₂, AB₃ . . . , AB_(n), respectively.

In one embodiment, a two-step conjugation assay [46] is followed to bindthe carboxylated PEG covered nanorods (SERS nanorods) with thecorresponding antibody, including an activation step and a conjugationstep.

Specifically, in the activation step, 4 ml of purified carboxylated SERSnanorods from the previous step is re-suspended in PBS buffer solutionusing sonic probe for several minutes. A mixture of NHS and EDC (0.012 geach) is added to the solution and stirred for 15 min. After that,unbound materials are washed off twice using centrifugation at 8000 rpmfor 10 min using PBS buffer.

In the conjugation step, the carboxyl-activated nanorods are redispersedin 5 ml PBS buffer solution. To each of the five prepared solutions, thecorresponding antibody is added (anti-EpCAM to AuNR/Ag/4MBA, anti-CD44to AuNR/Ag/PATP, anti-IGF-1 receptor (3 to AuNR/Ag/PNTP, Keratin18 toAuNR/Ag/4MSTP, and anti-CD45 to AuNR/Ag/4ADPS) and mixed thoroughly. Thereaction solution is stirred for 4 hours at room temperature. Afterthat, the antibody tagged nanorods (SERS nanoagents) are washed andre-suspended in 5 ml 1×PBS solution and kept under −20° C. for lateruse.

As described above, the formed targeting layer 218 may be an antibodylayer. The antibody layer 218 includes antibodies that are specificallytargeting certain cancer cell surface antigens. In one embodiment, theantibody are attached covalently with HS-PEG-COOH (—COOH terminal) andplays a role in the specific SERS nanocomposite delivery to the cancercells. In one embodiment, the antibody layer 218 includes at least oneof anti-EpCAM antibody, anti-CD44 antibody, anti-IGF-1 Receptor βantibody, anti-Keratin 18 antibody, and one or more antibodies specificto the target of interest.

In certain embodiments, the method further includes attaching one ormore molecules of interest to the binding layer 214 or the targetinglayer 218. In one embodiment, the molecule of interest is a growthfactor that induces certain biological functions, including the growth,proliferation of differentiation of cells or organisms. In oneembodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

Referring to FIG. 4 (A), schematic diagrams of preparing the four typesof SERS nanocomposites and the Raman spectra (acquisition time 50s)corresponding to each of the four types of SERS nanocomposites areprovided. Each color represents a unique AuNR/Ag covered by smallorganic compounds then a layer of HS-PEG-COOH and then a specific cancercell antibody layer, where the blue color representsAuNR/Ag/4MBA/anti-EpCAM, the red color representsAuNR/Ag/PNTP/anti-IGF-1 Receptorβ, the green color representsAuNR/Ag/PATP/anti-CD44, and the magenta color representsAuNR/Ag/4MSTP/anti-Keratin18. The nanocomposites containing 4MBA shows aspecific peak at 422 cm⁻¹, the nanocomposites containing PATP shows aspecific peak at 1372 cm⁻¹, the nanocomposites containing PNTP shows aspecific peak at 1312 cm⁻¹, and the nanocomposites containing 4MSTPshows a specific peak at 733 cm⁻¹.

In a further aspect, the present invention is directed to a system forat least one target detection by SERS. In certain embodiments, the atleast one target includes cancer cells. In certain embodiments, thesystem includes a nanoagent, a surface-enhanced Raman spectrometer, anda processing unit.

In certain embodiments, the nanoagent may include multiplenanocomposites prepared as described above. The multiple nanocompositesmay correspond to SERS signals of multiple colors. In certainembodiments, each nanocomposite may include a silver coated goldnanorod, a Raman reporter molecule layer assembled on the silver layer,a pegylated layer coated on the Raman reporter layer, and an antibodylayer conjugated to the pegylated layer, as described above. Thenanoagent may be applied, for example, to a blood sample or body fluidsample from a patient or a potential patient. Alternatively, thenanoagent may be applied, for example, by injection, to a patient. Dueto the specific targeting property of the antibody on the surface of thenanoagent, the nanoagent may specifically bind to, for example, one ormore cancer cells in the blood or other objects. Then an incidentradiation signal, e.g., a laser beam, may be applied to thesample/blood/object with the nanoagent, and SERS spectra are collectedusing the SERS signal from the nanoagent. The collected spectra areprocessed by the processing unit, such that the presence and/or thequantity of the one or more cancer cells or other targets can bedetermined.

In certain embodiments, the laser beam for SERS signal excitation may beone beam, or may be split in a multitude of sub-beams. In certainembodiments, the Raman spectra corresponding to the SERS agents could beintegrated in a 2D image. Moreover, the laser beam may be off-focusedsuch that the surface of analysis is increased.

In one embodiment, after necessary modification, the system may workwith other systems such as DualScan from Horiba or similar systems.

In certain embodiments, the report molecules may include one or morefluorescent agents. The one or more fluorescent agents can be quantumdots or fluorescent dyes. And the system includes an equipment that canbe used to detect the one or more fluorescent agents.

In yet another aspect, the present invention is directed to a method ofdetecting one or more targets, such as cancer cells, by SERS, using thesystem as described above.

In certain embodiments, the nanocomposite in the above described systemmay further include one or more molecules of interest for treating theone or more targets. In one embodiment, the molecule of interest is agrowth factor that induces certain biological functions, including thegrowth, proliferation of differentiation of cells or organisms. In oneembodiment, the molecule of interest is a protein, a drug, or abiological system that induces certain biological functions, the deathof cells, tissues, or organisms. The one or more drugs may be anticancerdrugs, antibiotics, or antiviral drugs.

Comparing with the structure and detection method in related art, thebiocompatible nanoagent and the method of using the nanoagent fordetecting at least one target, such as cancer cells, by SERS accordingto certain embodiments of the present invention, among other things, hasthe following advantages.

Firstly, SERS provides a high resolution, high sensitivity detectionmethod over conventional Raman method. Specifically, SERS signals aresignificant enhanced compared to the conventional Raman signal, allowingsignal collection from down to a single molecule level when variousnoble metals of rough surfaces or nanomaterials are used. Theenhancement factors for the Raman-scattering signals of SERS can be morethan one million-fold compared with normal Raman signals. Therefore,SERS has a significant potential to be used in bio-medical applications[9].

Secondly, in certain embodiments of the present invention, silver coatedgold nanorods (AuNR/Ag) are used to prepare the nanoagent for SERSdetection. The AuNR/Ag shows stronger spectroscopic properties comparedto AuNR [31] or silver nanoparticles. In one embodiment, metallicnano-silver does not suppress surface plasmons as strongly as nano-gold[31]. Further, the silver-gold interface (AuNR/Ag) core-shells have40-50% more light scattering capacity compared to pure AuNRs [30], whichmakes them excellent candidates for SERS bio-medical applications wheresingle molecule level detection limits are required. Accordingly, incertain embodiment, the AuNR/Ag in the nanoagent is superior to goldnanoparticles or silver nanoparticles.

Thirdly, in certain embodiments of the present invention, four differentantibodies against specific surface antigens of breast cancer cell lineMCF-7 are used for preparing the biocompatible nanocomposite for SERSdetection. The four antibodies include Anti-EpCam antibody, anti-CD44antibody, anti-keratin 18 antibody, and anti-IGF-I antibody. The fourcorresponding antigens are highly expressed in certain cancer cells,especially breast cancer cells. The four types of antibodies andcorresponding SERS reporter molecules can be represented by differentcolors in SERS detection. When the SERS signals represented by differentcolors are combined, the multicolor combination shows high sensitivityand accuracy than single color detection, and prevent signaloverlapping.

Examples Example 1 Preparing a Biocompatible Nanoagent

In all preparation procedures, deionized water (DI water, 18 Ω/cm) wasused. The following chemicals were purchased from Sigma-Aldrich and usedwithout further purification: Gold (III) chloride trihydrate (99%),sodium borohydride (99%), L-ascorbic acid (98%), 4-mercaptobenzoic acid(4MBA), p-aminothiophenol (PATP), p-nitrothiophenol (PNTP),4-methylsulfanylthiophenol (4MSTP), and 4-aminophenyldisulfide (4APDS),Polyvinylpyrrolidone (PVP) (MW˜10,000), N-hydroxysuccinimide (NHS),1N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC).Silver nitrate was purchased from Fisher Scientific.Hexadecyltrimethylammoniumbromide (CTAB 99%) was purchased from MPBiomedicals. SH-PEG (Mw˜5000) was purchased from Nanocs (95%).HS-PEG-COOH (Mw˜3000) was purchased from Sigma-Aldrich.

All antibodies used (anti-EpCAM, anti-CD44, anti-CD45, anti-IGF-1Receptor β, anti-cytokeratin18) were purchased from Cell Signaling athigh purity.

Human breast carcinoma cell line (MCF7) and fibroblast normal skin cellline were purchased from the American Type Culture Collection (ATCC).Culture media, including culture supplies, were purchased from FisherScientific.

In Example 1, the nan-agent according to certain embodiments of thepresent application was synthesized as follows.

Synthesis of gold nanorods: gold nanorods (AuNRs) with turned size wereprepared according to the seed mediated method by Nikoobakht [26].Briefly, the seed solution was first prepared by mixing 5 ml of 0.2 MCTAB solution with 5 ml of 0.0005 M HAuCl₄, and then adding 600 μl ofNaBH₄ with stirring for two minutes. To synthesize AuNRs with an aspectratio around 3, 5 ml of 0.2 M CTAB was mixed with 150 μl of 0.004 Msilver nitrate solution, then 5 ml of 0.001 M HAuCl₄ was added andmixed, after that 70 μl of 0.0788 M ascorbic acid was mixed with thesolution and finally 12 μl of seed solution was added. The mixedsolution was kept at 30° C. for 40 minutes without any further stirring.

Coating of AuNR with a thin shell silver layer to form a silver coatedgold nanorod (AuNR/Ag): the prepared AuNRs were covered with a thin (>1nm) silver layer, using the previously reported method [30, 44]. AuNRsfrom the synthesis step were purified by centrifugation (10,000 rpm, 30min) twice to remove any excess reagents, the precipitate wasre-dispersed in 5 ml CTAB solution by sonication, then 5 ml of 1% PVPsolution and 250 μl of 0.001 M AgNO₃ were added to AuNRs solution withgentle mixing. After that 100 μl of 0.1 M ascorbic acid was added and200 μl of NaOH solution was added to elevate the pH to around 9, inorder to initiate the silver ion reduction reaction.

Assembling SERS compounds on the surface of the AuNR/Ag: the AuNR/Agfrom the previous step were purified by centrifugation at 12,000 rpm andredispersed in deionized water, twice to remove any excess reagents.Thiophenol molecules can be self-assembled on the surface of the silverlayer [45]. Five thiophenol derivatives were prepared with 10 mM eachethanol based solution, in five separate conical flasks each contain 5ml of AuNR/Ag. 5 μl of 4MBA, PATP, PNTP, 4MSTP, or 4ADPS were addedseparately and kept under stirring for 3 hours at 45° C., this stepassured that a large portion of surface attached CTAB were replaced byRaman SERS molecules. Unabsorbed excess was removed by centrifugationonce at 10,000 rpm for 30 min.

Coating with HS-PEG and HS-PEG-COOH: each precipitate from the previousstep was redispersed in 2 ml HS-PEG-COOH (MW˜3000, 2 mg/ml in 2 mM NaCl)solution and vigorously stirred for 15 min, then 1.8 ml of HS-PEG (2mg/ml in 2 mM NaCl) solution was added and kept in contact with the SERSnanoagents at 5° C. overnight. After that, the unbound thiolated PEG wasremoved by centrifugation at 4,000 rpm for 15 min and redispersed usingprobe sonication twice. The precipitate for each coated nanorod solutionwas re-suspended in 1×PBS (phosphate buffer solution) solution.

Conjugation of coated SERS nanorods with antibodies: a two-stepconjugation assay [46] was followed to bind the carboxylated PEG coverednanorods (SERS nanorods) with the corresponding antibody.

Activation Step:

4 ml of purified carboxylated SERS nanorods from the previous step wasre-suspended in PBS buffer solution using sonic probe for severalminutes. A mixture of NHS and EDC (0.012 g each) was added to thesolution and stirred for 15 min. After that, unbound materials werewashed off twice using centrifugation at 8,000 rpm for 10 min and PBSbuffer.

Conjugation Step:

the carboxyl-activated nanorods were redispersed in 5 ml PBS buffersolution. To each of the five prepared solutions, the correspondingantibody was added (anti-EpCAM to AuNR/Ag/4MBA, anti-CD44 toAuNR/Ag/PATP, anti-IGF-1 receptor (3 to AuNR/Ag/PNTP, Keratin18 toAuNR/Ag/4MSTP, and anti-CD45 to AuNR/Ag/4ADPS) and mixed thoroughly. Thereaction solution was stirred at for 4 hours at room temperature. Afterthat, the antibody tagged nanorods (SERS nanoagents) were washed andre-suspended in 5 ml 1×PBS solution and kept under −20° C. for lateruse.

Characterization of the Nanoagent Prepared from Example 1

The nanoagents prepared from Example 1 were characterized by variety ofmethod, such as scanning electron microscopy (SEM), transmissionelectron microscopy (TEM), high resolution TEM (HRTEM), SERS, UV-Visspectroscopy.

For TEM characterization, the morphology and size of the gold nanorods(AuNRs) according to Example 1 were determined by TEM, JEM-2100F (JEOLUSA, Peabody, Mass., USA) with an accelerating voltage of 80 kV. Highresolution TEM (HRTEM) imaging was performed at 200 kV. A few drops eachof samples suspended in water were deposited on holey-carbon coatedcopper grids, which were then allowed to dry for 15 minutes on filterpapers. The average rod size and the size distribution of each samplewere determined by using Image J image analysis tool. The PEG-coatedgold nanorod and the protein coated gold nanorod samples were positivelystained with 2% uranyl acetate dissolved in 70% ethanol in order toenhance the protein coating layer around the AuNR. The TEM was alsoequipped with an EDAX Genesis energy dispersive spectroscopy (EDS) ofX-ray detection system. Combined with Scanning Transmission ElectronMicroscopy (STEM), elemental mapping of nanorods can be performed withclose to 1 nm lateral resolution Annular dark field (ADF) imaging underSTEM mode was performed with 1.5 nm spot size and 20 cm camera lengthwith a JEOL dark field detector.

For SEM characterization, MCF-7 cells were grown on Thermanox® plasticcoverslip (NUNC, Rochester, N.Y.) for 24 hours. Samples were treatedwith SERS nanoagents for 30 minutes. MCF-7 cells were fixed primarilywith 3% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2, followed by asecondary fixative of 2% OsO4 in 0.1 M phosphate buffer. All of thesamples were washed thoroughly with 0.1 M phosphate buffer, dehydratedwith ascending percentages of ethanol solution, and then dried usingHexamethyldisilazane (HMDS) reagent (EMS, Hatfield, Pa.). Each driedsample was coated with a thin film of carbon (˜3 nm) and visualizedunder a SEM, JEOL JSM-7000F (JEOL USA, Peabody, Mass.) also equippedwith an EDAX EDS detection system with an accelerating voltage of 15 kVand a working distance of ˜10 mm.

Referring to the HRTEM images as shown in (a1) and (a2) of FIG. 3 (A),the particle length and diameter of the AuNRs are approximately 36±0.80nm and 12±0.41 nm, respectively. Referring to the HRTEM images as shownin (a1) and (a2) of FIG. 3 (A), the silver film has a thickness of about1.7 nm.

FIG. 3 (B) shows images of AuNR/Ag, where (b1) is a SEM image, (b2) is aSTEM gold EDS element image, (b3) is a STEM silver EDS layer elementimage, (b4) is a STEM overlapped image, and (b5) is a EDS cross-scanningspectra. The result indicates that the silver atoms give the highesttendency for the outside layer arrangement in this bimetal composition.The thin silver layer helps maintain the longitudinal surface plasmonwavelength as close as possible to the excitation laser source (784 nm),in order to achieve the maximum SERS signal.

FIG. 5A and FIG. 5B show visualization of SERS nanoparticles on thecells' surface, where FIG. 5A shows SEM images with EDS elementalanalysis of nanocomposites on the MCF-7 cell surface according to oneembodiment of the present invention, and FIG. 5B shows TEM images ofnanocomposites cluster on the surface of an MCF-7 cell according to oneembodiment of the present invention. As shown in FIG. 5A, (a1) is a SEMimage of the nanorods cluster on a MCF7 cell surface, (a2) is an imageshowing Au EDS elemental analysis of the nanorods cluster, and (a3) isan merged image of the nanorods cluster. As shown in FIG. 5B, (b1, (b2),and (b3) are TEM images of the nanorods (SERS nanoagents) cluster on thesurface of an MCF7 cell with different magnification, showing how thenanorods accumulate on the surface of an MCF7 cell. FIGS. 5A and 5Bclearly show that the SERS nanoagents accumulated on the surface of thecells.

UV Visible Spectra: 100 μg/ml solution of AuNRs, AuNR/Ag, and all SERSnanoagents were scanned from 400-900 nm using Shimadzu (UV-Visible-NIR)spectrophotometer. The data was re-constructed using software.

FIG. 3 (C) shows UV-Vis spectra of AuNR and AuNR/Ag, and the insertedimage shows UV-Vis spectra of SERS nanoagents. As shown in FIG. 3 (C),the two dimensions, particle length and diameter of the AuNRs andAuNR/Ag, are adequate to form two kinds of surface plasmon modes: a weakone around 520 nm transvers mode, and a very strong longitudinal plasmonaround 766 nm [26]. The longitudinal surface plasmon is crucial, and themaximum excitation of this strong surface plasmon mode can be achievedwhen excited by a Raman excitation laser at about 784 nm. This ensuresultimate sensitivity and very low detection limits when uses SERS forcancer cell detection.

Further, the silver layer epitaxial growth on the gold nanorod surfacecan be confirmed by the absorbance spectra. Upon the silver layergrowth, the longitudinal band of gold nanorods showed a blue shift ofaround 20 nm (to about 740 nm), and there were no significant silverband appeared in the lower wavelength, which supposes to appear in thatrange if the silver completely covered the gold nanorods. This result isconsistent with the HRTEM images that a very thin layer of silver hasformed on the gold nanorod surface.

As shown in the inserted image of FIG. 3 (C), after the bioconjugationof the different types of antibodies on the surface of the silver coatedgold nanorod, there were still strong absorption in the UV-Vis spectrafor both longitudinal and transversal absorbance.

To evaluate the ability of anti-EpCam, CD44, Keratin 18, and IGF-Iantibodies to specifically target cancer cells, as well as todiscriminate between the two cell lines (MCF-7 and fibroblast),immunocytochemistry techniques were conducted. The antibody binding wasidentified by the use of a secondary antibody labeling method with fourdifferent colors.

Breast adenocarcinoma (MCF-7 cell line), and normal skin fibroblast(BJ-1 cell line) were co-cultured in two-well chamber slides in adensity of 15⁴ cells/well with the percentages of 90% fibroblastic BJ-1cells and 10% cancerous MCF-7 cells. The mixed cells were then incubatedfor 24 hours for attachment. Post incubation, the cells were washed with1× of phosphate buffer saline solution 3×5 min each. 200 μl of highpurity methanol was added to each well and incubated for 20 min at roomtemperature for fixation. The methanol was removed, and the cells werewashed with 1× of phosphate buffer saline solution 3×5 min each.Subsequently, 200 μl of blocking buffer containing (1×PBS/5% BSA) wasadded to each well and incubated for 30 min at room temperature. In themeantime, a 1:200 dilution of each antibody-Anti-EpCam, Anti-CD44,Anti-Keratin 18, and Anti IGF-I (Cell Signaling Technology, Boston,Mass.)—was prepared using blocking buffer in separate labeled tubes. Theblocking buffer was removed, and the diluted antibodies were added toeach well and incubated over night at 4° C. The cells were then washedwith 1× of phosphate buffer saline solution for 3×5 min each. Fourdifferent goat polyclonal secondary antibodies to mouse IgG withdifferent fluorescent properties—Alexa Flour 488, 555, 594, and 647(abcam, Cambridge, Mass.)—were used in a dilution of 1:500 with blockingbuffer. The secondary antibodies were added to each well and incubatedfor 1 h in the dark at room temperature. The cells were washed with 1×of phosphate buffer saline solution 3×5 min each, and then 200 μl of0.5% μg/ml of 4′,6-diamidino-2-phenylindole (DAPI) was added andincubated for 5 min at room temperature in the dark to perform nuclearstaining. The cells were mounted with mounting medium, covered with thecover slip, and the edges were sealed. Finally, the cells were kept inthe dark at 4° C. until examination under the fluorescence microscopeusing an Olympus BX 51 microscope.

FIG. 6 schematically shows the immunocytochemistry staining (ICC) ofMCF-7 cells in mixed culture with fibroblast cells BJ-1 according to oneembodiment of the present invention. As shown in FIG. 6, the top rowshows ICC of cells with anti-EpCAM, anti-CD44, anti-Keratin 18, andanti-IGF antibodies (1:200), respectively, followed by (1:500) goatanti-mouse IgG (Alexa fluor 555, 594, 488, and 647). The middle rowshows DAPI nuclear staining of both cell lines. The bottom row showsmerged images. The white arrows indicate the presence of antigenslocalized on the surface of breast cancer cells, and not on the surfaceof fibroblast cells.

As presented in FIG. 6, the anti-EpCAM antibody, anti-CD44, anti-Keratin18 and anti-IGF-I were found to selectively bind MCF-7 cancer cells andnot to the normal fibroblast cells. As a result, this method couldfacilitate the specific delivery of SERS nanoagents to breast cancercells only.

SERS: Referring back to FIG. 3 (D), the silver layer enhances the Ramansignal by a factor 129 times (SERS) compared to that of pure AuNR.

Example 2 Using the Prepared Nanoagent for Cancer Cell Detection by SERS

Breast adenocarcinoma (MCF-7 cell line) and skin fibroblast (BJ-1 cells)were purchased from American Type Culture Collection (ATCC). Both celllines were primarily cultured in 75 cm² tissue culture flasks andsupplemented with the recommended medium-Dulbecco minimum essentialmedium (DMEM), and Eagle's minimum essential medium (EMEM) respectively,both containing 10% fetal bovine serum (FBS) and 1% penicillinstreptomycin (PS), the cells were incubated at 37° C. in humidifiedincubator and 5% CO₂. The medium was changed every 48 h with freshmedium until confluent.

For SERS analysis, mixture of cancerous MCF7 cell line and BJ-1 cellline were seeded in 4 well chamber slides in a density of 10⁵ cells/welland a percentage of 90% BJ-1 cells, 10% MCF-7 cells. The cells weresupplemented with complete growth medium and incubated overnight forattachment. After incubation, the medium was interchanged with normalgrowth medium supplemented by 40 μg/ml of SERS nanoagents (10 μg of eachSERS nanoagents) and the cells were further incubated for 30 min at 37°C. The cells were washed for 5 minutes 3 times with 1×PBS, and 2%formaldehyde was added for fixation. After 20 min, the cells were washed6 times (3 times with 1×PBS, and 3 times with DI water). The cells wereleft to dry and stored at −20° C. Untreated cells were used as anegative control.

SERS images were collected from the samples using Confocal Ramanspectrometer (Horiba Jobin Yvon LabRam HR800, Edison, N.J.) assembledwith He—Ne laser (784 nm) and three Olympus BX-51 lenses with100×micro-objectives magnitude connected to a Peltier-cooled CCD camera.The spectra were collected using 600-line/mm gratings with the sameacquisition time. The spectrometer also has a three-dimensional (3-D)(x-y-z) automatic adjustable stage that can map Raman scanning for aspecific area at a minimum distance of 1 μm. In all measurements, theRaman spectrometer was calibrated using the Si—Si Raman signal, which islocated at a 521-cm⁻¹ Raman shift.

FIG. 7A shows Raman mapping images of cells according to embodiments ofthe present invention, where (a1) shows Raman mapping images fortargeting a single MCF-7 cancer cell among fibroblast cells with fourdifferent SERS nanoagents; (a2) shows Raman mapping images of a cancercell without using any SERS nanoagents; and (a3) shows Raman mappingimages of a fibroblast cell (normal cell) with four SERS nanoagents. Asshown in FIG. 7A, normal cells as shown in (a3) and MCF-7 cells withoutSERS nanoagent have not reveal any Raman signal in scanned regions.These Raman mapping images have clearly confirmed that multiple SERSnanocomposites (blue, red, green, and magenta referred to 4MBA, PNTP,PATP, 4MSTP respectively) of a nanoagent are simultaneously targetingthe same MCF-7 cell within 30 minutes of incubation with 8s Ramanacquisition time.

In order to detect the cancer cell MCF-7 in real blood or separatedwhite blood cells, a few of cancer cells (5, 50, 500 or 5000 cells)spiked with (100 μL) whole blood or the separated white blood cellsolution. In one embodiment, the two samples (separated blood and wholeblood) contain about 50 cancer cells in 7 million white blood cells.Then 50 μg/ml of SERS nanoagents mixture were added to incubate for 30minutes.

FIG. 7B shows Raman mapping images of cells according to certainembodiments of the present invention, where (b1) shows Raman mappingimages of a single cancer cell, MCF-7, among millions of white bloodcells, using a nanoagent having four types of nanocomposites; (b2) showsRaman mapping images of a single cancer cell, MCF-7, among millions ofwhole blood cells, using a nanoagent having four types ofnanocomposites; and (b3) shows SERS mapping signal collected from thewhite blood cells only, i.e., without presence of cancer cells, using ananoagent having four types of nanocomposites. As shown in (b1) and (b2)of FIG. 7B, four different colors show the four different SERSnanoagents were detected in the same cell which were located in thedifferent place of the cancer cell surface and some were overlapped eachother. However, signals from the four types of SERS nanocomposites canbe distinguished because of the colors, which means the specific Ramanpeaks. As shown in (b3) of FIG. 7B, there is no specific Raman signalfrom the white blood cells.

In order to estimate how fast SERS signal could be detected, an MCF7cell was targeted and scanned several times with different acquisitiontime (1s, 2s, 3s, 4s, 5s). FIG. 7C shows SERS signal collected withdifferent time periods from 1 second(s) to 5s, using a nanoagent havingfour types of nanocomposites according to one embodiment of the presentinvention. As shown in FIG. 7C, SERS signal could be significantlydetected mostly within 3s. The intensity of the Raman signal can bedetected variable from 1-8 s depended on the different antibodies of thenanocomposites. The SERS nanoagents having the multiple nanocompositeswere successfully targeted on the MCF-7 single cell and detected byRaman among millions of fibroblast cells.

FIG. 7D schematically shows SERS linear scanning position and SERSsignal of a selected single cancer cell according to one embodiment ofthe present invention, where (d1) shows SERS linear scanning position ofa selected single cancer cell, and (d2) shows SERS signal of a selectedsingle cancer cell scanned linearly four times along the line in FIG. 7D(d1), each time with a specific scanning range corresponding to one ofthe four types of SERS nanocomposites. As shown in FIG. 7D, a singlecancer cell was selected and scanned linearly four times, each time witha specific scanning range corresponding to that specific SERS nanoagent.FIG. 7D shows that SERS signals come from only the MCF-7 cell and thereis no significant signal from the blood cells.

In order to ensure that SERS nanoagent having multiple type ofnanocomposites were selectively targeting MCF-7 cells because they aredirected to these cells by the antibodies, a negative SERS nanoagent wasprepared and tested. Anti-CD45 is a biomolecule known to target whiteblood cells rather than the MCF-7 cells. The negative SERS nanocompositeof AuNR/Ag/4ADPS/CD45 was prepared and incubated with the same sample ofmixed white blood cells and few MCF-7. SERS images were then collectedto see if any signal from the cancer cells was received. The resultswere in complete agreement with our hypothesis, where the SERS signalwas obtained from the white blood cells and not from the cancer cells.

FIG. 8 shows images of SERS signal of a mixture of MCF-7 cell and whiteblood cells, using the negative nanocomposite having CD45, according tocertain embodiments of the present invention. As shown in (a1) to (a3)of FIG. 8, there was no SERS signal from the MCF-7 cell and all SERSsignal coming from the white blood cells, when using the negativenanoagents having CD45.

In summary, according to certain embodiment of the present invention, itis able to detect SERS signals from a single cancer cell among millionsof blood cells in a short period of time. The nanostructural agents,formed of four types of silver decorated gold nanorods, were designed tohave high optical absorption in the near-infrared region (NIR) and tomatch the emission of the laser excitation. All four SERS nano-reporterswere used for the multicolor superimposed identification of the cancercells. Each agent, with unique spectral features, was assigned adifferent color and the identification of the individual cancer cells inblood was performed based on the overlapping of four colors in a2-dimensional scanning environment. SERS using those nanoagent cansuccessfully detect and image with high resolution a low population ofbreast cancer cells in peripheral blood or separated white blood cells(for example, 1 in 1 million). Such a multi-spectroscopic approachoffers the opportunities of accurate and high sensitivity detection ofsingle cancer cell in blood, given narrow SERS bandwidths of thenano-reporter spectra. Thus, certain embodiments of the presentinvention provide ultrafast and high specificity detection of the earlyclinical detection of a multitude of cancer cells or various pathogensin blood.

In the past, CTCs were thought to spread only during the final stages ofmalignant progression [41, 42]. However, recent researches havedemonstrated that CTCs also can be found in the bloodstream during earlystages [43]. Consequently, the fast detection of CTCs has become majorimpact factor for treatment and providing information about theaggressiveness of a tumor, how well patients are responding totreatment, and why some patients do not respond to a specific therapy.Certain methods usually required an enrichment and separation steps ofcancerous cells from normal cell which is tedious and time consumingprocedures [41]. However, comparing with related art, the presentinvention, for the first time, is able to detect a single cancer cell(CTC) quickly and within 1 to 7 million of blood erythrocytes cellswithout any enrichment assay.

The foregoing description of the exemplary embodiments of the inventionhas been presented only for the purposes of illustration and descriptionand is not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Many modifications and variations are possiblein light of the above teaching.

The embodiments were chosen and described in order to explain theprinciples of the invention and their practical application so as toenable others skilled in the art to utilize the invention and variousembodiments and with various modifications as are suited to theparticular use contemplated. Alternative embodiments will becomeapparent to those skilled in the art to which the invention pertainswithout departing from its spirit and scope. Accordingly, the scope ofthe invention is defined by the appended claims as well as the inventionincluding drawings.

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What is claimed is:
 1. A nanoagent for surface enhanced Ramanspectroscopy (SERS) detection of a target of interest, comprising atleast one nanocomposite, wherein the nanocomposite comprises: at leastone gold nanorod; a silver layer coated on an outer surface of the goldnanorod, comprising silver nanoparticles; a Raman reporter moleculelayer coated on the silver layer; a pegylated layer coated on the Ramanreporter molecule layer, comprising at least one of thiolatedpolyethylene glycol (HS-PEG), thiolated polyethylene glycol acid(HS-PEG-COOH) and HS-PEG-NHx; and an antibody layer conjugated to thepegylated layer, comprising molecules of an antibody or a combination ofantibodies.
 2. The nanoagent of claim 1, wherein the gold nanorod has anaspect ratio (AR) in a range of about 1-9.
 3. The nanoagent of claim 2,wherein the gold nanorod has the AR in a range of 2-5.
 4. The nanoagentof claim 1, wherein the gold nanorod has a length in a range of about10-100 nm and a diameter in a range of about 1-40 nm, respectively. 5.The nanoagent of claim 4, wherein the gold nanorod has the length in arange of about 35.20-36.80 nm and the diameter in a range of about11.59-12.41 nm, respectively.
 6. The nanoagent of claim 1, wherein thesilver layer has a thickness in a range of about 0.5-5 nm.
 7. Thenanoagent of claim 6, wherein the silver layer has the thickness ofabout 1-2 nm.
 8. The nanoagent of claim 1, wherein the Raman reporterlayer comprises 4-mercaptobenzoic acid (4MBA), p-aminothiophenol (PATP),p-nitrothiophenol (PNTP), 4-(methylsulfanyl) thiophenol (4MSTP), orother molecules with unique Raman spectra and intense Raman peakintensities.
 9. The nanoagent of claim 1, wherein the HS-PEG has amolecular weight in a range of about 1.5-15 kilo Dalton (kD) and theHS-PEG-COOH has a molecular weight in a range of about 1-10 kD.
 10. Thenanoagent of claim 9, wherein the HS-PEG has the molecular weight ofabout 5 kD and the HS-PEG-COOH has the molecular weight of about 3 kD.11. The nanoagent of claim 1, wherein the molecules of the antibody areconjugated to the pegylated layer through the carboxylic group of theHS-PEG-COOH or amine group of the HS-PEG-NHx.
 12. The nanoagent of claim1, wherein the antibody comprises anti-epithelial cell adhesion moleculeantibody (anti-EpCAM), anti-CD44 antibody, anti-insulin-like growthfactor 1 receptor antibody (anti-IGF-1), anti-Keratin 18 antibody, orone or more antibodies specific to the target of interest.
 13. Thenanoagent of claim 1, wherein the at least one nanocomposite comprises afirst nanocomposite, a second nanocomposite, a third nanocomposite, anda fourth nanocomposite; wherein the Raman reporter layer of the firstnanocomposite comprises 4-mercaptobenzoic acid (4MBA), and the antibodyof the first nanocomposite is anti-epithelial cell adhesion moleculeantibody (anti-EpCAM); wherein the Raman reporter layer of the secondnanocomposite comprises p-aminothiophenol (PATP), and the antibody ofthe second nanocomposite is anti-CD44 antibody; wherein the Ramanreporter layer of the third nanocomposite comprises p-nitrothiophenol(PNTP), and the antibody of the third nanocomposite is anti-insulin-likegrowth factor 1 receptor antibody (anti-IGF-1); and wherein the Ramanreporter layer of the fourth nanocomposite comprises 4-(methylsulfanyl)thiophenol (4MSTP), and the antibody of the fourth nanocomposite isanti-Keratin 18 antibody.
 14. The nanoagent of claim 1, wherein SERSsignal corresponding to each nanocomposite is represented by apredetermined color.
 15. The nanoagent of claim 1, wherein the target ofinterest comprises at least one tumor cell or at least one pathogen. 16.The nanoagent of claim 1, further comprising at least one molecule ofinterest attached to the pegylated layer or the antibody layer of thenanocomposite, wherein the molecule of interest is a drug, a growthfactor, a protein, or other biologically active molecules.
 17. Thenanoagent of claim 1, further comprising at least one fluorescent agentattached to the nanocomposite.
 18. A nanocomposite, comprising: a core;a shell surrounding the core; a reporter layer assembled on the shell;and a targeting layer conjugated to the reporter layer, comprisingtargeting molecules.
 19. The nanocomposite of claim 18, wherein the corecomprises at least one gold nanorod, and the shell is a silver layercomprising silver nanoparticles.
 20. The nanocomposite of claim 18,wherein the reporter layer is detectable by at least one of surfaceenhanced Raman spectroscopy (SERS), magnetic resonance imaging (MRI),x-ray radiography, computed tomography (CT), and infrared spectroscopy(IR).
 21. The nanocomposite of claim 18, wherein the reporter layercomprises 4-mercaptobenzoic acid (4MBA), p-aminothiophenol (PATP),p-nitrothiophenol (PNTP), 4-(methylsulfanyl) thiophenol (4MSTP), orother molecules with unique Raman spectra and intense Raman peakintensities.
 22. The nanocomposite of claim 18, further comprising apegylated layer disposed between the reporter layer and the targetinglayer, wherein the pegylated layer comprises at least one of thiolatedpolyethylene glycol (HS-PEG), thiolated polyethylene glycol acid(HS-PEG-COOH) and HS-PEG-NHx.
 23. The nanocomposite of claim 18, whereinthe targeting molecules are molecules of anti-epithelial cell adhesionmolecule antibody (anti-EpCAM), anti-CD44 antibody, anti-insulin-likegrowth factor 1 receptor antibody (anti-IGF-1), anti-Keratin 18antibody, or one or more antibodies specific to a target of interest.24. The nanocomposite of claim 18, further comprising at least onemolecule of interest selected from a drug, a growth factor, a protein,or other biologically active molecules.
 25. The nanocomposite of claim18, further comprising at least one fluorescent agent.
 26. A nanoagentcomprising at least one nanocomposite of claim 18, for detecting atleast one tumor cell or at least one pathogen.
 27. A system fordetecting a target of interest, comprising: a nanoagent having at leastone nanocomposite, wherein each nanocomposite comprises: at least onegold nanorod; a silver layer coated on an outer surface of the goldnanorod, comprising silver nanoparticles; a Raman reporter moleculelayer assembled on the silver layer; a pegylated layer coated on theRaman reporter molecule layer, comprising at least one of thiolatedpolyethylene glycol (HS-PEG), thiolated polyethylene glycol acid(HS-PEG-COOH) and HS-PEG-NHx; and an antibody layer conjugated to thepegylated layer, comprising molecules of an antibody; a surface enhancedRaman spectrometer configured to provide an incident radiation signal tothe target of interest, and to collect surface enhanced Ramanspectroscopy (SERS) signals generated by the Raman reporter moleculelayer in response to the incident radiation signal; and a processingunit for processing the SERS signals collected by the surface enhancedRaman spectrometer, so as to determine whether the target of interesthas at least one tumor cell or at least one pathogen.
 28. The system ofclaim 27, wherein the at least one nanocomposite comprises a firstnanocomposite, a second nanocomposite, a third nanocomposite, and afourth nanocomposite; wherein the Raman reporter molecule layer of thefirst nanocomposite comprises 4-mercaptobenzoic acid (4MBA), and theantibody of the first nanocomposite is anti-epithelial cell adhesionmolecule antibody (anti-EpCAM); wherein the Raman reporter moleculelayer of the second nanocomposite comprises p-aminothiophenol (PATP),and the antibody of the second nanocomposite is anti-CD44 antibody;wherein the Raman reporter molecule layer of the third nanocompositecomprises p-nitrothiophenol (PNTP), and the antibody of the thirdnanocomposite is anti-insulin-like growth factor 1 receptor antibody(anti-IGF-1); and wherein the Raman reporter molecule layer of thefourth nanocomposite comprises 4-(methylsulfanyl) thiophenol (4MSTP),and the antibody of the fourth nanocomposite is anti-Keratin 18antibody.
 29. The system of claim 28, wherein the SERS signalscorresponding to the first, the second, the third, and the fourthnanocomposites are characterized with different colors respectively. 30.The system of claim 27, wherein the nanorod has an aspect ratio (AR) ina range of about 2-5.
 31. The system of claim 27, wherein the nanorodhas a length in a range of about 35.20-36.80 nm and a diameter in arange of about 11.59-12.41 nm, respectively.
 32. The system of claim 27,wherein the silver layer has a thickness of about 1-2 nm.
 33. The systemof claim 27, wherein the HS-PEG has a molecular weight of about 5 kiloDalton (kD) and the HS-PEG-COOH has a molecular weight of about 3 kD.34. The system of claim 27, wherein the target of interest comprises atleast one tumor cell or at least one pathogen.
 35. The system of claim27, further comprising at least one molecule of interest attached to thenanocomposite, wherein the molecule of interest is a drug, a growthfactor, a protein, or other biologically active molecules.
 36. Thesystem of claim 27, further comprising at least one fluorescent agentattached to the nanocomposite.
 37. A method of making at least onenanocomposite for surface enhanced Raman spectroscopy (SERS) detectionof a target of interest, comprising: forming at least one gold nanorod;coating a silver layer on an outer surface of the gold nanorod;assembling a Raman reporter molecule layer on the coated silver layer,wherein the Raman reporter molecule layer comprises Raman reportermolecules that are detectable by the SERS; coating a thiolatedpolyethylene glycol (PEG) layer on the assembled Raman reporter moleculelayer; and conjugating the coated thiolated PEG layer with molecules ofan antibody to make the at least one nanocomposite.
 38. The method ofclaim 37, wherein the step of forming the at least one gold nanorodcomprises: mixing a first exadecyltrimethylammoniumbromide (CTAB)solution with a silver nitrate solution to form a first mixture; addinga first HAuCl₄ to the first mixture to form a second mixture; adding afirst ascorbic acid to the second mixture to form a third mixture;adding a seed solution to the third mixture to form a fourth mixture;and centrifuging the fourth mixture to form a first precipitate, whereinthe first precipitate comprises the gold nanorod.
 39. The method ofclaim 38, wherein the seed solution is prepared by: mixing a second CTABsolution with a second HAuCl₄ to form a fifth mixture; and adding NaBH₄to the fifth mixture and stirring to form the seed solution.
 40. Themethod of claim 37, wherein the step of coating the silver layercomprises: dispersing the gold nanorod in a third CTAB solution bysonication to form a sixth mixture; adding a polyvinylpyrrolidone (PVP)solution and AgNO₃ to the sixth mixture and gently mixing to form aseventh mixture; adding a second ascobic acid to the seventh mixture toform an eighth mixture; adding NaOH solution to the eighth mixture toform a ninth mixture, such that the pH of the ninth mixture is elevatedto about pH 9, and a silver ion reduction reaction is initiated; andcentrifuging the ninth mixture to form a second precipitate, wherein thesecond precipitate comprises the gold nanorod coated with the silverlayer.
 41. The method of claim 37, wherein the step of assembling theRaman reporter molecule layer comprises: dispersing the gold nanorodcoated with the silver layer in distilled water to form a tenth mixture;dissolving the Raman reporter molecule comprising 4-mercaptobenzoic acid(4-MBA), p-aminothiophenol (PATP), p-nitrothiophenol (PNTP), or4-(methylsulfanyl) thiophenol (4-MSTP), in ethanol to form a reportersolution; adding the reporter solution to the tenth mixture and stirringto form an eleventh mixture; and centrifuging the eleventh mixture toform a third precipitate, wherein the third precipitate comprises thegold nanorod coated with the silver layer, and assembled with the Ramanreport molecule layer.
 42. The method of claim 37, wherein the step ofcoating the thiolated PEG layer comprises: dispersing the gold nanorodwith the coated silver layer and the assembled Raman reporter layer inthiolated polyethylene glycol acid (HS-PEG-COOH) solution and vigorouslystirring to form a twelfth mixture, wherein the HS-PEG-COOH solutioncomprises about 2 mg/ml HS-PEG and about 2 mM NaCl; adding thiolatedpolyethylene glycol (HS-PEG) to the twelfth mixture and keep at about 5°C. overnight to form a thirteenth mixture; and centrifuging thethirteenth mixture to form a fourth precipitate, wherein the fourthprecipitate comprises the gold nanorod coated with the silver layer,assembled with the Raman report molecule layer, and coated with thethiolated PEG layer.
 43. The method of claim 37, wherein the step ofconjugating the coated thiolated PEG layer with the molecules of theantibody comprises: suspending the gold nanorod with the coated silverlayer, the assembled Raman reporter layer, and the coated thiolated PEGlayer in PBS buffer by sonicating to form a suspending mixture; addingN-hydroxysuccinimide (NHS) and 1N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) to the suspending mixture and stirringto form a fourteenth mixture; washing the fourteenth mixture bycentrifuging twice using PBS buffer to obtain a fifth precipitate;dispensing the fifth precipitate in PBS buffer to form a fifteenmixture; adding molecules of the antibody to the fifteenth mixture andmixing thoroughly to form a sixteen mixture, wherein the antibodycomprises anti-EpCAM, anti-CD44, anti-IGF-1 Receptor β, anti-Keratin 18,or one or more antibodies specific to the target of interest; andstirring the sixteenth mixture at room temperature to form thenanocomposite.
 44. The method of claim 37, wherein SERS signalcorresponding to each nanocomposite is characterized with apredetermined color.
 45. The method of claim 37, wherein the target ofinterest comprises at least one tumor cell or at least one pathogen. 46.The method of claim 37, further comprising: attaching at least onemolecule of interest to the nanocomposite, wherein the molecule ofinterest is a drug, a growth factor, a protein, or other biologicallyactive molecules.
 47. The method of claim 37, further comprisingattaching at least one fluorescent agent to the nanocomposite.
 48. Amethod of making a nanoagent, comprising: forming the at least onenanocomposite according to the method of claim 37; and making thenanoagent using the at least one nanocomposite.